Why Google uses this?

[smallcompany]

I just updated my ads in PPC. The folder and file names have changed. I used Google AdWords editor and pushed the changes.
That is obvious to trigger Google's system to check and verify the changes, no problem.

I made mistakes in few ad groups which resulted on 404, and in notification email I got those IPs:

64.233.172.x
64.233.173.x
74.125.75.x

and the user agent was:

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)

All IPs belong to Google.

Now:

Why Google does not identify itself in a better manner, because I block user agents of this type based on my previous experience with similar?

P.S.
There was one more 404 that came from AdsBot-Google. If other IPs were for something else, still related to AdWords, heck, mark it somehow so I don't block it.

[incrediBILL]

Not all IP activity from Google is a bot.

I suspect that's a human checking your landing page and they may be using Trend Micro or AVG that checks your site for malicious content before the human gets the page.

[smallcompany]

Makes sense.

But, the only user agent that caused 404 was that one, there was no other UA which would allude to a manual process.

So it stands that this could be a part of automated check and that UA has initiated my ads to get disapproved.

I wonder what would happen if I banned it...

[Bewenched]

I see accesses from google that have a user agent of Safari

[jdMorgan]

Bewnenched,

Are they Safari requests, or Safari-based Google Chrome requests? Does the report you're looking at distinguish between these two?

Smallco,

As IncrediBill pointed out, that MSIE UA is used by Trend Micro, so do be careful just banning it.

Jim